if you applied for a loan online the company should be sending you Master Promissory Notes (some places make them available online in pdf format, so check to see if you have an online account with the lender). There are separate MPNs for Stafford and Grad PLUS loans, you will need to sign both. Then, from what I gather, the lender contacts your school to make sure you are eligible for the funding you requested. The school says yes he is, they tell the lender when the disbursement date should be and that is about it. After that I believe the school gives you the money that is intended for non-tuition expenses.
Correct me if I'm wrong about any of this stuff, I was in roughly the same place about 2 weeks ago.